A main circuit in a radio communication device is often formed by a CMOS process, for integration on a chip. For example, a local oscillation signal can be generated by an all-digitized all digital phase-locked loop (ADPLL) circuit and a time to digital converter.
A conventional time to digital converter latches each output of multi-staged inverters with a corresponding flip-flop to generate a phase difference signal. This type of circuit requires several-tens-staged inverters and flip-flops so that there is a problem that a circuit scale increases and additionally the consumption current of the entire time to digital converter is large.